Module: xenomai-forge
Branch: master
Commit: 59fadd67ea418a7449a841fa9a72ce420b51e1c0
URL:    
http://git.xenomai.org/?p=xenomai-forge.git;a=commit;h=59fadd67ea418a7449a841fa9a72ce420b51e1c0

Author: Wolfgang Grandegger <w...@grandegger.com>
Date:   Sun Aug 26 15:41:04 2012 +0200

cobalt/drivers/serial: introduce driver for IMX SOCs UARTs

This RTserial driver is for the Freescale IMX internal UART compatible
controllers. It has been tested with Freescale's 3.0.15 kernel on an
i.MX53 and i.MX6Q board but it should work with more recent mainline
kernel versions as well. The modem control and line state is handled
similar to the 16550A UART, if possible. But this part is still weak
and not very well tested.

Signed-off-by: Wolfgang Grandegger <w...@denx.de>

---

 kernel/drivers/serial/Kconfig       |    8 +
 kernel/drivers/serial/Makefile      |    2 +
 kernel/drivers/serial/rt_imx_uart.c | 1560 +++++++++++++++++++++++++++++++++++
 3 files changed, 1570 insertions(+), 0 deletions(-)

diff --git a/kernel/drivers/serial/Kconfig b/kernel/drivers/serial/Kconfig
index 80abd86..e495911 100644
--- a/kernel/drivers/serial/Kconfig
+++ b/kernel/drivers/serial/Kconfig
@@ -68,4 +68,12 @@ config XENO_DRIVERS_MPC52XX_UART
        help
        Real-time UART driver for the PSC on the MPC5200 processor.
 
+config XENO_DRIVERS_IMX_UART
+       depends on XENO_SKIN_RTDM && (ARCH_IMX || ARCH_MXC)
+       tristate "RT IMX UART driver"
+       select RATIONAL
+       help
+       Real-time UART driver for the Freescale Semiconductor MXC Internal
+       UART compatible controllers.
+
 endmenu
diff --git a/kernel/drivers/serial/Makefile b/kernel/drivers/serial/Makefile
index 9885c4a..3ac292b 100644
--- a/kernel/drivers/serial/Makefile
+++ b/kernel/drivers/serial/Makefile
@@ -3,6 +3,8 @@ ccflags-y := -D__IN_XENOMAI__ -Iinclude/xenomai/cobalt 
-Iinclude/xenomai
 
 obj-$(CONFIG_XENO_DRIVERS_16550A) += xeno_16550A.o
 obj-$(CONFIG_XENO_DRIVERS_MPC52XX_UART) += xeno_mpc52xx_uart.o
+obj-$(CONFIG_XENO_DRIVERS_IMX_UART) += xeno_imx_uart.o
 
 xeno_16550A-y := 16550A.o
 xeno_mpc52xx_uart-y := mpc52xx_uart.o
+xeno_imx_uart-y := rt_imx_uart.o
diff --git a/kernel/drivers/serial/rt_imx_uart.c 
b/kernel/drivers/serial/rt_imx_uart.c
new file mode 100644
index 0000000..73b420e
--- /dev/null
+++ b/kernel/drivers/serial/rt_imx_uart.c
@@ -0,0 +1,1560 @@
+/*
+ * Copyright 2012 Wolfgang Grandegger <w...@denx.de>
+ *
+ * Derived from the Linux IMX UART driver (drivers/tty/serial/imx.c)
+ * and 16650A RTserial driver.
+ *
+ * Copyright (C) 2005-2007 Jan Kiszka <jan.kis...@web.de>.
+ * Copyright (C) 2004 Pengutronix
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/tty.h>
+#include <linux/string.h>
+#include <linux/ioport.h>
+#include <linux/init.h>
+#include <linux/serial.h>
+#include <linux/console.h>
+#include <linux/platform_device.h>
+#include <linux/sysrq.h>
+#include <linux/dma-mapping.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/rational.h>
+#include <linux/io.h>
+#include <asm/irq.h>
+#include <asm/dma.h>
+#include <asm/div64.h>
+#include <mach/hardware.h>
+#include <mach/imx-uart.h>
+
+#include <rtdm/rtserial.h>
+#include <rtdm/rtdm_driver.h>
+
+#define DRIVER_NAME    "xeno_imx_uart"
+
+/* Register definitions */
+#define URXD0  0x0  /* Receiver Register */
+#define URTX0  0x40 /* Transmitter Register */
+#define UCR1   0x80 /* Control Register 1 */
+#define UCR2   0x84 /* Control Register 2 */
+#define UCR3   0x88 /* Control Register 3 */
+#define UCR4   0x8c /* Control Register 4 */
+#define UFCR   0x90 /* FIFO Control Register */
+#define USR1   0x94 /* Status Register 1 */
+#define USR2   0x98 /* Status Register 2 */
+#define UESC   0x9c /* Escape Character Register */
+#define UTIM   0xa0 /* Escape Timer Register */
+#define UBIR   0xa4 /* BRM Incremental Register */
+#define UBMR   0xa8 /* BRM Modulator Register */
+#define UBRC   0xac /* Baud Rate Count Register */
+#define MX2_ONEMS 0xb0 /* One Millisecond register */
+#define UTS (cpu_is_mx1() ? 0xd0 : 0xb4) /* UART Test Register */
+
+/* UART Control Register Bit Fields.*/
+#define URXD_CHARRDY   (1<<15)
+#define URXD_ERR       (1<<14)
+#define URXD_OVRRUN    (1<<13)
+#define URXD_FRMERR    (1<<12)
+#define URXD_BRK       (1<<11)
+#define URXD_PRERR     (1<<10)
+#define UCR1_ADEN      (1<<15) /* Auto dectect interrupt */
+#define UCR1_ADBR      (1<<14) /* Auto detect baud rate */
+#define UCR1_TRDYEN    (1<<13) /* Transmitter ready interrupt enable */
+#define UCR1_IDEN      (1<<12) /* Idle condition interrupt */
+#define UCR1_RRDYEN    (1<<9)  /* Recv ready interrupt enable */
+#define UCR1_RDMAEN    (1<<8)  /* Recv ready DMA enable */
+#define UCR1_IREN      (1<<7)  /* Infrared interface enable */
+#define UCR1_TXMPTYEN  (1<<6)  /* Transimitter empty interrupt enable */
+#define UCR1_RTSDEN    (1<<5)  /* RTS delta interrupt enable */
+#define UCR1_SNDBRK    (1<<4)  /* Send break */
+#define UCR1_TDMAEN    (1<<3)  /* Transmitter ready DMA enable */
+#define MX1_UCR1_UARTCLKEN     (1<<2)  /* UART clock enabled, mx1 only */
+#define UCR1_DOZE      (1<<1)  /* Doze */
+#define UCR1_UARTEN    (1<<0)  /* UART enabled */
+#define UCR2_ESCI      (1<<15) /* Escape seq interrupt enable */
+#define UCR2_IRTS      (1<<14) /* Ignore RTS pin */
+#define UCR2_CTSC      (1<<13) /* CTS pin control */
+#define UCR2_CTS       (1<<12) /* Clear to send */
+#define UCR2_ESCEN     (1<<11) /* Escape enable */
+#define UCR2_PREN      (1<<8)  /* Parity enable */
+#define UCR2_PROE      (1<<7)  /* Parity odd/even */
+#define UCR2_STPB      (1<<6)  /* Stop */
+#define UCR2_WS                (1<<5)  /* Word size */
+#define UCR2_RTSEN     (1<<4)  /* Request to send interrupt enable */
+#define UCR2_TXEN      (1<<2)  /* Transmitter enabled */
+#define UCR2_RXEN      (1<<1)  /* Receiver enabled */
+#define UCR2_SRST      (1<<0)  /* SW reset */
+#define UCR3_DTREN     (1<<13) /* DTR interrupt enable */
+#define UCR3_PARERREN  (1<<12) /* Parity enable */
+#define UCR3_FRAERREN  (1<<11) /* Frame error interrupt enable */
+#define UCR3_DSR       (1<<10) /* Data set ready */
+#define UCR3_DCD       (1<<9)  /* Data carrier detect */
+#define UCR3_RI                (1<<8)  /* Ring indicator */
+#define UCR3_TIMEOUTEN (1<<7)  /* Timeout interrupt enable */
+#define UCR3_RXDSEN    (1<<6)  /* Receive status interrupt enable */
+#define UCR3_AIRINTEN  (1<<5)  /* Async IR wake interrupt enable */
+#define UCR3_AWAKEN    (1<<4)  /* Async wake interrupt enable */
+#define MX1_UCR3_REF25         (1<<3)  /* Ref freq 25 MHz, only on mx1 */
+#define MX1_UCR3_REF30         (1<<2)  /* Ref Freq 30 MHz, only on mx1 */
+#define MX2_UCR3_RXDMUXSEL     (1<<2)  /* RXD Muxed Input Select, on mx2/mx3 */
+#define UCR3_INVT      (1<<1)  /* Inverted Infrared transmission */
+#define UCR3_BPEN      (1<<0)  /* Preset registers enable */
+#define UCR4_CTSTL_SHF 10      /* CTS trigger level shift */
+#define UCR4_CTSTL_MASK        0x3F    /* CTS trigger is 6 bits wide */
+#define UCR4_INVR      (1<<9)  /* Inverted infrared reception */
+#define UCR4_ENIRI     (1<<8)  /* Serial infrared interrupt enable */
+#define UCR4_WKEN      (1<<7)  /* Wake interrupt enable */
+#define UCR4_REF16     (1<<6)  /* Ref freq 16 MHz */
+#define UCR4_IRSC      (1<<5)  /* IR special case */
+#define UCR4_TCEN      (1<<3)  /* Transmit complete interrupt enable */
+#define UCR4_BKEN      (1<<2)  /* Break condition interrupt enable */
+#define UCR4_OREN      (1<<1)  /* Receiver overrun interrupt enable */
+#define UCR4_DREN      (1<<0)  /* Recv data ready interrupt enable */
+#define UFCR_RXTL_SHF  0       /* Receiver trigger level shift */
+#define UFCR_RFDIV     (7<<7)  /* Reference freq divider mask */
+#define UFCR_RFDIV_REG(x)      (((x) < 7 ? 6 - (x) : 6) << 7)
+#define UFCR_TXTL_SHF  10      /* Transmitter trigger level shift */
+#define UFCR_DCEDTE    (1<<6)
+#define USR1_PARITYERR (1<<15) /* Parity error interrupt flag */
+#define USR1_RTSS      (1<<14) /* RTS pin status */
+#define USR1_TRDY      (1<<13) /* Transmitter ready interrupt/dma flag */
+#define USR1_RTSD      (1<<12) /* RTS delta */
+#define USR1_ESCF      (1<<11) /* Escape seq interrupt flag */
+#define USR1_FRAMERR   (1<<10) /* Frame error interrupt flag */
+#define USR1_RRDY      (1<<9)  /* Receiver ready interrupt/dma flag */
+#define USR1_AGTIM     (1<<8)  /* Ageing Timer Interrupt Flag */
+#define USR1_DTRD      (1<<7)  /* DTR Delta */
+#define USR1_RXDS      (1<<6)  /* Receiver idle interrupt flag */
+#define USR1_AIRINT    (1<<5)  /* Async IR wake interrupt flag */
+#define USR1_AWAKE     (1<<4)  /* Aysnc wake interrupt flag */
+#define USR2_ADET      (1<<15) /* Auto baud rate detect complete */
+#define USR2_TXFE      (1<<14) /* Transmit buffer FIFO empty */
+#define USR2_DTRF      (1<<13) /* DTR edge interrupt flag */
+#define USR2_IDLE      (1<<12) /* Idle condition */
+#define USR2_RIDELT    (1<<10) /* Ring Indicator Delta */
+#define USR2_RIIN      (1<<9)  /* Ring Indicator Input */
+#define USR2_IRINT     (1<<8)  /* Serial infrared interrupt flag */
+#define USR2_WAKE      (1<<7)  /* Wake */
+#define USR2_DCDDELT   (1<<6)  /* Data Carrier Detect Delta */
+#define USR2_DCDIN     (1<<5)  /* Data Carrier Detect Input */
+#define USR2_RTSF      (1<<4)  /* RTS edge interrupt flag */
+#define USR2_TXDC      (1<<3)  /* Transmitter complete */
+#define USR2_BRCD      (1<<2)  /* Break condition */
+#define USR2_ORE       (1<<1)  /* Overrun error */
+#define USR2_RDR       (1<<0)  /* Recv data ready */
+#define UTS_FRCPERR    (1<<13) /* Force parity error */
+#define UTS_LOOP       (1<<12) /* Loop tx and rx */
+#define UTS_TXEMPTY    (1<<6)  /* TxFIFO empty */
+#define UTS_RXEMPTY    (1<<5)  /* RxFIFO empty */
+#define UTS_TXFULL     (1<<4)  /* TxFIFO full */
+#define UTS_RXFULL     (1<<3)  /* RxFIFO full */
+#define UTS_SOFTRST    (1<<0)  /* Software reset */
+
+#define IN_BUFFER_SIZE         4096
+#define OUT_BUFFER_SIZE                4096
+
+#define TX_FIFO_SIZE           32
+
+#define PARITY_MASK            0x03
+#define DATA_BITS_MASK         0x03
+#define STOP_BITS_MASK         0x01
+#define FIFO_MASK              0xC0
+#define EVENT_MASK             0x0F
+
+#define IER_RX                 0x01
+#define IER_TX                 0x02
+#define IER_STAT               0x04
+#define IER_MODEM              0x08
+
+#define IMX_ISR_PASS_LIMIT     256
+#define UART_CREAD_BIT         256
+
+#define RT_IMX_UART_MAX                5
+
+static int tx_fifo[RT_IMX_UART_MAX];
+compat_module_param_array(tx_fifo, int, RT_IMX_UART_MAX, 0400);
+MODULE_PARM_DESC(tx_fifo, "Transmitter FIFO size");
+
+static unsigned int start_index;
+module_param(start_index, uint, 0400);
+MODULE_PARM_DESC(start_index, "First device instance number to be used");
+
+struct rt_imx_uart_port {
+       unsigned char __iomem *membase; /* read/write[bwl] */
+       resource_size_t mapbase;        /* for ioremap */
+       unsigned int irq;               /* irq number */
+       int tx_fifo;                    /* TX fifo size*/
+       unsigned int have_rtscts;
+       unsigned int use_dcedte;
+       unsigned int use_hwflow;
+       struct clk *clk;                /* clock id for UART clock */
+       unsigned int uartclk;           /* base uart clock */
+       struct rtdm_device rtdm_dev;    /* RTDM device structure */
+};
+
+struct rt_imx_uart_ctx {
+       struct rtser_config config;     /* current device configuration */
+
+       rtdm_irq_t irq_handle;          /* device IRQ handle */
+       rtdm_lock_t lock;               /* lock to protect context struct */
+
+       int in_head;                    /* RX ring buffer, head pointer */
+       int in_tail;                    /* RX ring buffer, tail pointer */
+       size_t in_npend;                /* pending bytes in RX ring */
+       int in_nwait;                   /* bytes the user waits for */
+       rtdm_event_t in_event;          /* raised to unblock reader */
+       char in_buf[IN_BUFFER_SIZE];    /* RX ring buffer */
+       volatile unsigned long in_lock; /* single-reader lock */
+       uint64_t *in_history;           /* RX timestamp buffer */
+
+       int out_head;                   /* TX ring buffer, head pointer */
+       int out_tail;                   /* TX ring buffer, tail pointer */
+       size_t out_npend;               /* pending bytes in TX ring */
+       rtdm_event_t out_event;         /* raised to unblock writer */
+       char out_buf[OUT_BUFFER_SIZE];  /* TX ring buffer */
+       rtdm_mutex_t out_lock;          /* single-writer mutex */
+
+       uint64_t last_timestamp;        /* timestamp of last event */
+       int ioc_events;                 /* recorded events */
+       rtdm_event_t ioc_event;         /* raised to unblock event waiter */
+       volatile unsigned long ioc_event_lock;  /* single-waiter lock */
+
+       int ier_status;                 /* IER cache */
+       int mcr_status;                 /* MCR cache */
+       int status;                     /* cache for LSR + soft-states */
+       int saved_errors;               /* error cache for RTIOC_GET_STATUS */
+
+       /*
+        * The port structure holds all the information about the UART
+        * port like base address, and so on.
+        */
+       struct rt_imx_uart_port *port;
+};
+
+static const struct rtser_config default_config = {
+       .config_mask = 0xFFFF,
+       .baud_rate = RTSER_DEF_BAUD,
+       .parity = RTSER_DEF_PARITY,
+       .data_bits = RTSER_DEF_BITS,
+       .stop_bits = RTSER_DEF_STOPB,
+       .handshake = RTSER_DEF_HAND,
+       .fifo_depth = RTSER_DEF_FIFO_DEPTH,
+       .rx_timeout = RTSER_DEF_TIMEOUT,
+       .tx_timeout = RTSER_DEF_TIMEOUT,
+       .event_timeout = RTSER_DEF_TIMEOUT,
+       .timestamp_history = RTSER_DEF_TIMESTAMP_HISTORY,
+       .event_mask = RTSER_DEF_EVENT_MASK,
+};
+
+static void rt_imx_uart_stop_tx(struct rt_imx_uart_ctx *ctx)
+{
+       unsigned long temp;
+
+       temp = readl(ctx->port->membase + UCR1);
+       writel(temp & ~UCR1_TXMPTYEN, ctx->port->membase + UCR1);
+}
+
+static void rt_imx_uart_start_tx(struct rt_imx_uart_ctx *ctx)
+{
+       unsigned long temp;
+
+       temp = readl(ctx->port->membase + UCR1);
+       writel(temp | UCR1_TXMPTYEN, ctx->port->membase + UCR1);
+}
+
+static void rt_imx_uart_enable_ms(struct rt_imx_uart_ctx *ctx)
+{
+       unsigned long ucr3;
+
+       /*
+        * RTS interrupt is enabled only if we are using interrupt-driven
+        * software controlled hardware flow control
+        */
+       if (!ctx->port->use_hwflow) {
+               unsigned long ucr1 = readl(ctx->port->membase + UCR1);
+
+               ucr1 |= UCR1_RTSDEN;
+               writel(ucr1, ctx->port->membase + UCR1);
+       }
+       ucr3 = readl(ctx->port->membase + UCR3);
+       ucr3 |= UCR3_DTREN;
+       if (ctx->port->use_dcedte) /* DTE mode */
+               ucr3 |= UCR3_DCD | UCR3_RI;
+       writel(ucr3, ctx->port->membase + UCR3);
+}
+
+static int rt_imx_uart_rx_chars(struct rt_imx_uart_ctx *ctx,
+                               uint64_t *timestamp)
+{
+       unsigned int rx, temp, max_count = 256;
+       int rbytes = 0;
+       int lsr = 0;
+
+       while ((readl(ctx->port->membase + USR2) & USR2_RDR) &&
+              (max_count-- > 0)) {
+               rx = readl(ctx->port->membase + URXD0);
+               temp = readl(ctx->port->membase + USR2);
+               if (temp & USR2_BRCD) {
+                       writel(USR2_BRCD, ctx->port->membase + USR2);
+                       lsr |= RTSER_LSR_BREAK_IND;
+               }
+
+               if (rx & (URXD_PRERR | URXD_OVRRUN | URXD_FRMERR)) {
+                       if (rx & URXD_PRERR)
+                               lsr |= RTSER_LSR_PARITY_ERR;
+                       else if (rx & URXD_FRMERR)
+                               lsr |= RTSER_LSR_FRAMING_ERR;
+                       if (rx & URXD_OVRRUN)
+                               lsr |= RTSER_LSR_OVERRUN_ERR;
+               }
+
+               /* save received character */
+               ctx->in_buf[ctx->in_tail] = rx & 0xff;
+               if (ctx->in_history)
+                       ctx->in_history[ctx->in_tail] = *timestamp;
+               ctx->in_tail = (ctx->in_tail + 1) & (IN_BUFFER_SIZE - 1);
+
+               if (++ctx->in_npend > IN_BUFFER_SIZE) {
+                       lsr |= RTSER_SOFT_OVERRUN_ERR;
+                       ctx->in_npend--;
+               }
+
+               rbytes++;
+       }
+
+       /* save new errors */
+       ctx->status |= lsr;
+
+       return rbytes;
+}
+
+static void rt_imx_uart_tx_chars(struct rt_imx_uart_ctx *ctx)
+{
+       int ch, count;
+
+       for (count = ctx->port->tx_fifo;
+            (count > 0) && (ctx->out_npend > 0);
+            count--, ctx->out_npend--) {
+               ch = ctx->out_buf[ctx->out_head++];
+               writel(ch, ctx->port->membase + URTX0);
+               ctx->out_head &= (OUT_BUFFER_SIZE - 1);
+
+               if (readl(ctx->port->membase + UTS) & UTS_TXFULL)
+                       break;
+       }
+}
+
+static int rt_imx_uart_modem_status(struct rt_imx_uart_ctx *ctx,
+                                    unsigned int usr1,
+                                    unsigned int usr2)
+{
+       int events = 0;
+
+       /* Clear the status bits that triggered the interrupt */
+       writel(usr1, ctx->port->membase + USR1);
+       writel(usr2, ctx->port->membase + USR2);
+
+       if (ctx->port->use_dcedte) { /* DTE mode */
+               if (usr2 & USR2_DCDDELT)
+                       events |= !(usr2 & USR2_DCDIN) ?
+                               RTSER_EVENT_MODEMHI : RTSER_EVENT_MODEMLO;
+       }
+       if (!ctx->port->use_hwflow && (usr1 & USR1_RTSD)) {
+               events |= (usr1 & USR1_RTSS) ?
+                       RTSER_EVENT_MODEMHI : RTSER_EVENT_MODEMLO;
+       }
+
+       return events;
+}
+
+static int rt_imx_uart_int(rtdm_irq_t *irq_context)
+{
+       uint64_t timestamp = rtdm_clock_read();
+       struct rt_imx_uart_ctx *ctx;
+       unsigned int usr1, usr2, ucr1;
+       int rbytes = 0;
+       int events = 0;
+       int ret = RTDM_IRQ_NONE;
+
+       ctx = rtdm_irq_get_arg(irq_context, struct rt_imx_uart_ctx);
+
+       rtdm_lock_get(&ctx->lock);
+
+       usr1 = readl(ctx->port->membase + USR1);
+       usr2 = readl(ctx->port->membase + USR2);
+       ucr1 = readl(ctx->port->membase + UCR1);
+
+       /*
+        * Read if there is data available
+        */
+       if (usr1 & USR1_RRDY) {
+               rbytes += rt_imx_uart_rx_chars(ctx, &timestamp);
+               events |= RTSER_EVENT_RXPEND;
+               ret = RTDM_IRQ_HANDLED;
+       }
+
+       /*
+        * Send data if there is data to be sent
+        */
+       if ((usr1 & USR1_TRDY) && (ucr1 & UCR1_TXMPTYEN)) {
+               rt_imx_uart_tx_chars(ctx);
+               ret = RTDM_IRQ_HANDLED;
+       }
+
+       /*
+        * Handle modem status events
+        */
+       if ((usr1 & (USR1_RTSD | USR1_DTRD)) ||
+           (usr2 & (USR2_DCDDELT | USR2_RIDELT))) {
+               events |= rt_imx_uart_modem_status(ctx, usr1, usr2);
+               ret = RTDM_IRQ_HANDLED;
+       }
+
+       if (ctx->in_nwait > 0) {
+               if ((ctx->in_nwait <= rbytes) || ctx->status) {
+                       ctx->in_nwait = 0;
+                       rtdm_event_signal(&ctx->in_event);
+               } else {
+                       ctx->in_nwait -= rbytes;
+               }
+       }
+
+       if (ctx->status) {
+               events |= RTSER_EVENT_ERRPEND;
+#ifdef FIXME
+               ctx->ier_status &= ~IER_STAT;
+#endif
+       }
+
+       if (testbits(events, ctx->config.event_mask)) {
+               int old_events = ctx->ioc_events;
+
+               ctx->last_timestamp = timestamp;
+               ctx->ioc_events = events;
+
+               if (!old_events)
+                       rtdm_event_signal(&ctx->ioc_event);
+       }
+
+       if (testbits(ctx->ier_status, IER_TX) && (ctx->out_npend == 0)) {
+               rt_imx_uart_stop_tx(ctx);
+               ctx->ier_status &= ~IER_TX;
+               rtdm_event_signal(&ctx->out_event);
+       }
+
+       rtdm_lock_put(&ctx->lock);
+
+       if (ret != RTDM_IRQ_HANDLED)
+               printk(KERN_WARNING "%s: unhandled interrupt\n", __func__);
+       return ret;
+}
+
+static unsigned int rt_imx_uart_get_msr(struct rt_imx_uart_ctx *ctx)
+{
+       unsigned long usr1 = readl(ctx->port->membase + USR1);
+       unsigned long usr2 = readl(ctx->port->membase + USR2);
+       unsigned int msr = 0;
+
+       if (usr1 & USR1_RTSD)
+               msr |= RTSER_MSR_DCTS;
+       if (usr1 & USR1_DTRD)
+               msr |= RTSER_MSR_DDSR;
+       if (usr2 & USR2_RIDELT)
+               msr |= RTSER_MSR_TERI;
+       if (usr2 & USR2_DCDDELT)
+               msr |= RTSER_MSR_DDCD;
+
+       if (usr1 & USR1_RTSS)
+               msr |= RTSER_MSR_CTS;
+
+       if (ctx->port->use_dcedte) { /* DTE mode */
+               if (!(usr2 & USR2_DCDIN))
+                       msr |= RTSER_MSR_DCD;
+               if (!(usr2 & USR2_RIIN))
+                       msr |= RTSER_MSR_RI;
+       }
+
+       return msr;
+}
+
+static void rt_imx_uart_set_mcr(struct rt_imx_uart_ctx *ctx,
+                               unsigned int mcr)
+{
+       unsigned long ucr2 = readl(ctx->port->membase + UCR2);
+       unsigned long ucr3 = readl(ctx->port->membase + UCR3);
+       unsigned long uts = readl(ctx->port->membase + UTS);
+
+       if (mcr & RTSER_MCR_RTS) {
+               /*
+                * Return to hardware-driven hardware flow control if the
+                * option is enabled
+                */
+               if (ctx->port->use_hwflow) {
+                       ucr2 |= UCR2_CTSC;
+               } else {
+                       ucr2 |= UCR2_CTS;
+                       ucr2 &= ~UCR2_CTSC;
+               }
+       } else {
+               ucr2 &= ~(UCR2_CTS | UCR2_CTSC);
+       }
+       writel(ucr2, ctx->port->membase + UCR2);
+
+       if (mcr & RTSER_MCR_DTR)
+               ucr3 |= UCR3_DSR;
+       else
+               ucr3 &= ~UCR3_DSR;
+       writel(ucr3, ctx->port->membase + UCR3);
+
+       if (mcr & RTSER_MCR_LOOP)
+               uts |= UTS_LOOP;
+       else
+               uts &= ~UTS_LOOP;
+       writel(uts, ctx->port->membase + UTS);
+}
+
+static void rt_imx_uart_break_ctl(struct rt_imx_uart_ctx *ctx,
+                                 int break_state)
+{
+       unsigned long ucr1 = readl(ctx->port->membase + UCR1);
+
+       if (break_state == RTSER_BREAK_SET)
+               ucr1 |= UCR1_SNDBRK;
+       else
+               ucr1 &= ~UCR1_SNDBRK;
+       writel(ucr1, ctx->port->membase + UCR1);
+}
+
+static int rt_imx_uart_set_config(struct rt_imx_uart_ctx *ctx,
+                                 const struct rtser_config *config,
+                                 uint64_t **in_history_ptr)
+{
+       rtdm_lockctx_t lock_ctx;
+       int err = 0;
+
+       rtdm_lock_get_irqsave(&ctx->lock, lock_ctx);
+
+       if (testbits(config->config_mask, RTSER_SET_BAUD))
+               ctx->config.baud_rate = config->baud_rate;
+       if (testbits(config->config_mask, RTSER_SET_DATA_BITS))
+               ctx->config.data_bits = config->data_bits & DATA_BITS_MASK;
+       if (testbits(config->config_mask, RTSER_SET_PARITY))
+               ctx->config.parity = config->parity & PARITY_MASK;
+       if (testbits(config->config_mask, RTSER_SET_STOP_BITS))
+               ctx->config.stop_bits = config->stop_bits & STOP_BITS_MASK;
+
+       /* Timeout manipulation is not atomic. The user is supposed to take
+          care not to use and change timeouts at the same time. */
+       if (testbits(config->config_mask, RTSER_SET_TIMEOUT_RX))
+               ctx->config.rx_timeout = config->rx_timeout;
+       if (testbits(config->config_mask, RTSER_SET_TIMEOUT_TX))
+               ctx->config.tx_timeout = config->tx_timeout;
+       if (testbits(config->config_mask, RTSER_SET_TIMEOUT_EVENT))
+               ctx->config.event_timeout = config->event_timeout;
+
+       if (testbits(config->config_mask, RTSER_SET_TIMESTAMP_HISTORY)) {
+               if (testbits
+                   (config->timestamp_history, RTSER_RX_TIMESTAMP_HISTORY)) {
+                       if (!ctx->in_history) {
+                               ctx->in_history = *in_history_ptr;
+                               *in_history_ptr = NULL;
+                               if (!ctx->in_history)
+                                       err = -ENOMEM;
+                       }
+               } else {
+                       *in_history_ptr = ctx->in_history;
+                       ctx->in_history = NULL;
+               }
+       }
+
+       if (testbits(config->config_mask, RTSER_SET_EVENT_MASK)) {
+               ctx->config.event_mask = config->event_mask & EVENT_MASK;
+               ctx->ioc_events = 0;
+
+               if (testbits(config->event_mask, RTSER_EVENT_RXPEND) &&
+                   (ctx->in_npend > 0))
+                       ctx->ioc_events |= RTSER_EVENT_RXPEND;
+
+               if (testbits(config->event_mask, RTSER_EVENT_ERRPEND)
+                   && ctx->status)
+                       ctx->ioc_events |= RTSER_EVENT_ERRPEND;
+       }
+
+       if (testbits(config->config_mask, RTSER_SET_HANDSHAKE)) {
+               ctx->config.handshake = config->handshake;
+
+               switch (ctx->config.handshake) {
+               case RTSER_RTSCTS_HAND:
+                       /* ...? */
+
+               default:        /* RTSER_NO_HAND */
+                       ctx->mcr_status = RTSER_MCR_RTS | RTSER_MCR_OUT1;
+                       break;
+               }
+               rt_imx_uart_set_mcr(ctx, ctx->mcr_status);
+       }
+
+       /* configure hardware with new parameters */
+       if (testbits(config->config_mask, (RTSER_SET_BAUD |
+                                          RTSER_SET_PARITY |
+                                          RTSER_SET_DATA_BITS |
+                                          RTSER_SET_STOP_BITS |
+                                          RTSER_SET_EVENT_MASK |
+                                          RTSER_SET_HANDSHAKE))) {
+               struct rt_imx_uart_port *port = ctx->port;
+               unsigned int ucr2, old_ucr1, old_txrxen;
+               unsigned int baud = ctx->config.baud_rate;
+               unsigned int div, ufcr;
+               unsigned long num, denom;
+               uint64_t tdiv64;
+
+               if (ctx->config.data_bits == RTSER_8_BITS)
+                       ucr2 = UCR2_WS | UCR2_SRST | UCR2_IRTS;
+               else
+                       ucr2 = UCR2_SRST | UCR2_IRTS;
+
+               if (ctx->config.handshake == RTSER_RTSCTS_HAND) {
+                       if (port->have_rtscts) {
+                               ucr2 &= ~UCR2_IRTS;
+                               ucr2 |= UCR2_CTSC;
+                       }
+               }
+
+               if (ctx->config.stop_bits == RTSER_2_STOPB)
+                       ucr2 |= UCR2_STPB;
+               if (ctx->config.parity == RTSER_ODD_PARITY ||
+                   ctx->config.parity == RTSER_EVEN_PARITY) {
+                       ucr2 |= UCR2_PREN;
+                       if (ctx->config.parity == RTSER_ODD_PARITY)
+                               ucr2 |= UCR2_PROE;
+               }
+
+               /*
+                * disable interrupts and drain transmitter
+                */
+               old_ucr1 = readl(port->membase + UCR1);
+               old_ucr1 &= ~UCR1_RTSDEN; /* reset in  rt_imx_uart_enable_ms()*/
+               writel(old_ucr1 & ~(UCR1_TXMPTYEN | UCR1_RRDYEN),
+                      port->membase + UCR1);
+               while (!(readl(port->membase + USR2) & USR2_TXDC))
+                       barrier();
+
+               /* then, disable everything */
+               old_txrxen = readl(port->membase + UCR2);
+               writel(old_txrxen & ~(UCR2_TXEN | UCR2_RXEN),
+                      port->membase + UCR2);
+               old_txrxen &= (UCR2_TXEN | UCR2_RXEN);
+               div = port->uartclk / (baud * 16);
+               if (div > 7)
+                       div = 7;
+               if (!div)
+                       div = 1;
+
+               rational_best_approximation(16 * div * baud, port->uartclk,
+                                           1 << 16, 1 << 16, &num, &denom);
+
+               tdiv64 = port->uartclk;
+               tdiv64 *= num;
+               do_div(tdiv64, denom * 16 * div);
+
+               num -= 1;
+               denom -= 1;
+
+               ufcr = readl(port->membase + UFCR);
+               ufcr = (ufcr & (~UFCR_RFDIV)) | UFCR_RFDIV_REG(div);
+
+               if (port->use_dcedte)
+                       ufcr |= UFCR_DCEDTE;
+
+               writel(ufcr, port->membase + UFCR);
+
+               writel(num, port->membase + UBIR);
+               writel(denom, port->membase + UBMR);
+
+               writel(port->uartclk / div / 1000, port->membase + MX2_ONEMS);
+
+               writel(old_ucr1, port->membase + UCR1);
+
+               /* set the parity, stop bits and data size */
+               writel(ucr2 | old_txrxen, port->membase + UCR2);
+
+               if (testbits(config->event_mask,
+                            RTSER_EVENT_MODEMHI | RTSER_EVENT_MODEMLO))
+                       rt_imx_uart_enable_ms(ctx);
+
+               ctx->status = 0;
+               ctx->ioc_events &= ~RTSER_EVENT_ERRPEND;
+       }
+
+       rtdm_lock_put_irqrestore(&ctx->lock, lock_ctx);
+
+       return err;
+}
+
+void rt_imx_uart_cleanup_ctx(struct rt_imx_uart_ctx *ctx)
+{
+       rtdm_event_destroy(&ctx->in_event);
+       rtdm_event_destroy(&ctx->out_event);
+       rtdm_event_destroy(&ctx->ioc_event);
+       rtdm_mutex_destroy(&ctx->out_lock);
+}
+
+#define TXTL 2 /* reset default */
+#define RXTL 1 /* reset default */
+
+static int rt_imx_uart_setup_ufcr(struct rt_imx_uart_port *port)
+{
+       unsigned int val;
+       unsigned int ufcr_rfdiv;
+
+       /* set receiver / transmitter trigger level.
+        * RFDIV is set such way to satisfy requested uartclk value
+        */
+       val = TXTL << 10 | RXTL;
+       ufcr_rfdiv = (clk_get_rate(port->clk) + port->uartclk / 2) /
+               port->uartclk;
+
+       if (!ufcr_rfdiv)
+               ufcr_rfdiv = 1;
+
+       val |= UFCR_RFDIV_REG(ufcr_rfdiv);
+
+       writel(val, port->membase + UFCR);
+
+       return 0;
+}
+
+/* half the RX buffer size */
+#define CTSTL 16
+
+static int rt_imx_uart_open(struct rtdm_dev_context *context,
+                           rtdm_user_info_t *user_info, int oflags)
+{
+       struct rt_imx_uart_ctx *ctx;
+       struct rt_imx_uart_port *port;
+       rtdm_lockctx_t lock_ctx;
+       unsigned long temp;
+       int retval;
+       uint64_t *dummy;
+
+       ctx = (struct rt_imx_uart_ctx *)context->dev_private;
+       ctx->port = (struct rt_imx_uart_port *)context->device->device_data;
+
+       port = ctx->port;
+
+       /* IPC initialisation - cannot fail with used parameters */
+       rtdm_lock_init(&ctx->lock);
+       rtdm_event_init(&ctx->in_event, 0);
+       rtdm_event_init(&ctx->out_event, 0);
+       rtdm_event_init(&ctx->ioc_event, 0);
+       rtdm_mutex_init(&ctx->out_lock);
+
+       ctx->in_head = 0;
+       ctx->in_tail = 0;
+       ctx->in_npend = 0;
+       ctx->in_nwait = 0;
+       ctx->in_lock = 0;
+       ctx->in_history = NULL;
+
+       ctx->out_head = 0;
+       ctx->out_tail = 0;
+       ctx->out_npend = 0;
+
+       ctx->ioc_events = 0;
+       ctx->ioc_event_lock = 0;
+       ctx->status = 0;
+       ctx->saved_errors = 0;
+
+       rt_imx_uart_setup_ufcr(port);
+
+       /*
+        * disable the DREN bit (Data Ready interrupt enable) before
+        * requesting IRQs
+        */
+       temp = readl(port->membase + UCR4);
+
+       /* set the trigger level for CTS */
+       temp &= ~(UCR4_CTSTL_MASK << UCR4_CTSTL_SHF);
+       temp |= CTSTL << UCR4_CTSTL_SHF;
+       writel(temp & ~UCR4_DREN, port->membase + UCR4);
+
+       rt_imx_uart_set_config(ctx, &default_config, &dummy);
+
+       retval = rtdm_irq_request(&ctx->irq_handle,
+                                 port->irq, rt_imx_uart_int, 0,
+                                 context->device->proc_name, ctx);
+       if (retval)
+               return retval;
+
+       rtdm_lock_get_irqsave(&ctx->lock, lock_ctx);
+
+       /*
+        * Finally, clear status and enable interrupts
+        */
+       writel(0xFFFF, port->membase + USR1);
+       writel(0xFFFF, port->membase + USR2);
+
+       temp = readl(port->membase + UCR1);
+       temp |= UCR1_RRDYEN  | UCR1_UARTEN;
+       writel(temp, port->membase + UCR1);
+
+       temp = readl(port->membase + UCR2);
+       temp |= (UCR2_RXEN | UCR2_TXEN);
+       writel(temp, port->membase + UCR2);
+
+       temp = readl(port->membase + UCR3);
+       temp |= MX2_UCR3_RXDMUXSEL;
+       writel(temp, port->membase + UCR3);
+
+       rtdm_lock_put_irqrestore(&ctx->lock, lock_ctx);
+
+       return 0;
+}
+
+int rt_imx_uart_close(struct rtdm_dev_context *context,
+                     rtdm_user_info_t *user_info)
+{
+       struct rt_imx_uart_ctx *ctx;
+       uint64_t *in_history;
+       rtdm_lockctx_t lock_ctx;
+       unsigned long temp;
+
+       ctx = (struct rt_imx_uart_ctx *)context->dev_private;
+
+       rtdm_lock_get_irqsave(&ctx->lock, lock_ctx);
+
+       temp = readl(ctx->port->membase + UCR2);
+       temp &= ~(UCR2_TXEN);
+       writel(temp, ctx->port->membase + UCR2);
+
+       /*
+        * Disable all interrupts, port and break condition.
+        */
+       temp = readl(ctx->port->membase + UCR1);
+       temp &= ~(UCR1_TXMPTYEN | UCR1_RRDYEN | UCR1_RTSDEN | UCR1_UARTEN);
+       writel(temp, ctx->port->membase + UCR1);
+
+       in_history = ctx->in_history;
+       ctx->in_history = NULL;
+
+       rtdm_lock_put_irqrestore(&ctx->lock, lock_ctx);
+
+       rtdm_irq_free(&ctx->irq_handle);
+       rt_imx_uart_cleanup_ctx(ctx);
+
+       if (in_history)
+               kfree(in_history);
+
+       return 0;
+}
+
+static int rt_imx_uart_ioctl(struct rtdm_dev_context *context,
+                            rtdm_user_info_t *user_info,
+                            unsigned int request, void *arg)
+{
+       rtdm_lockctx_t lock_ctx;
+       struct rt_imx_uart_ctx *ctx;
+       int err = 0;
+
+       ctx = (struct rt_imx_uart_ctx *)context->dev_private;
+
+       switch (request) {
+       case RTSER_RTIOC_GET_CONFIG:
+               if (user_info)
+                       err =
+                           rtdm_safe_copy_to_user(user_info, arg,
+                                                  &ctx->config,
+                                                  sizeof(struct rtser_config));
+               else
+                       memcpy(arg, &ctx->config,
+                              sizeof(struct rtser_config));
+               break;
+
+       case RTSER_RTIOC_SET_CONFIG: {
+               struct rtser_config *config;
+               struct rtser_config config_buf;
+               uint64_t *hist_buf = NULL;
+
+               config = (struct rtser_config *)arg;
+
+               if (user_info) {
+                       err =
+                           rtdm_safe_copy_from_user(user_info, &config_buf,
+                                                    arg,
+                                                    sizeof(struct
+                                                           rtser_config));
+                       if (err)
+                               return err;
+
+                       config = &config_buf;
+               }
+
+               if (testbits(config->config_mask, RTSER_SET_BAUD) &&
+                   (config->baud_rate > clk_get_rate(ctx->port->clk) / 16 ||
+                    config->baud_rate <= 0))
+                       /* invalid baudrate for this port */
+                       return -EINVAL;
+
+               if (testbits(config->config_mask,
+                            RTSER_SET_TIMESTAMP_HISTORY)) {
+                       /*
+                        * Reflect the call to non-RT as we will likely
+                        * allocate or free the buffer.
+                        */
+                       if (rtdm_in_rt_context())
+                               return -ENOSYS;
+
+                       if (testbits(config->timestamp_history,
+                                    RTSER_RX_TIMESTAMP_HISTORY))
+                               hist_buf = kmalloc(IN_BUFFER_SIZE *
+                                                  sizeof(nanosecs_abs_t),
+                                                  GFP_KERNEL);
+               }
+
+               rt_imx_uart_set_config(ctx, config, &hist_buf);
+
+               if (hist_buf)
+                       kfree(hist_buf);
+
+               break;
+       }
+
+       case RTSER_RTIOC_GET_STATUS: {
+               int status, msr;
+
+               rtdm_lock_get_irqsave(&ctx->lock, lock_ctx);
+
+               status = ctx->saved_errors | ctx->status;
+               ctx->status = 0;
+               ctx->saved_errors = 0;
+               ctx->ioc_events &= ~RTSER_EVENT_ERRPEND;
+
+               msr = rt_imx_uart_get_msr(ctx);
+
+               rtdm_lock_put_irqrestore(&ctx->lock, lock_ctx);
+
+               if (user_info) {
+                       struct rtser_status status_buf;
+
+
+                       status_buf.line_status = status;
+                       status_buf.modem_status = msr;
+                       err =
+                           rtdm_safe_copy_to_user(user_info, arg,
+                                                  &status_buf,
+                                                  sizeof(struct
+                                                         rtser_status));
+               } else {
+                       ((struct rtser_status *)arg)->line_status = 0;
+                       ((struct rtser_status *)arg)->modem_status = msr;
+               }
+               break;
+       }
+
+       case RTSER_RTIOC_GET_CONTROL:
+               if (user_info)
+                       err =
+                           rtdm_safe_copy_to_user(user_info, arg,
+                                                  &ctx->mcr_status,
+                                                  sizeof(int));
+               else
+                       *(int *)arg = ctx->mcr_status;
+
+               break;
+
+       case RTSER_RTIOC_SET_CONTROL: {
+               int new_mcr = (long)arg;
+
+               rtdm_lock_get_irqsave(&ctx->lock, lock_ctx);
+               ctx->mcr_status = new_mcr;
+               rt_imx_uart_set_mcr(ctx, new_mcr);
+               rtdm_lock_put_irqrestore(&ctx->lock, lock_ctx);
+               break;
+       }
+
+       case RTSER_RTIOC_WAIT_EVENT: {
+               struct rtser_event ev = { .rxpend_timestamp = 0 };
+               rtdm_toseq_t timeout_seq;
+
+               if (!rtdm_in_rt_context())
+                       return -ENOSYS;
+
+               /* Only one waiter allowed, stop any further attempts here. */
+               if (test_and_set_bit(0, &ctx->ioc_event_lock))
+                       return -EBUSY;
+
+               rtdm_toseq_init(&timeout_seq, ctx->config.event_timeout);
+
+               rtdm_lock_get_irqsave(&ctx->lock, lock_ctx);
+
+               while (!ctx->ioc_events) {
+                       /* Only enable error interrupt
+                          when the user waits for it. */
+                       if (testbits(ctx->config.event_mask,
+                                    RTSER_EVENT_ERRPEND)) {
+                               ctx->ier_status |= IER_STAT;
+#ifdef FIXME
+                               rt_imx_uart_reg_out(mode, base, IER,
+                                                ctx->ier_status);
+#endif
+                       }
+
+                       rtdm_lock_put_irqrestore(&ctx->lock, lock_ctx);
+
+                       err = rtdm_event_timedwait(&ctx->ioc_event,
+                                                  ctx->config.event_timeout,
+                                                  &timeout_seq);
+                       if (err) {
+                               /* Device has been closed? */
+                               if (err == -EIDRM)
+                                       err = -EBADF;
+                               goto wait_unlock_out;
+                       }
+
+                       rtdm_lock_get_irqsave(&ctx->lock, lock_ctx);
+               }
+
+               ev.events = ctx->ioc_events;
+               ctx->ioc_events &=
+                   ~(RTSER_EVENT_MODEMHI | RTSER_EVENT_MODEMLO);
+
+               ev.last_timestamp = ctx->last_timestamp;
+               ev.rx_pending = ctx->in_npend;
+
+               if (ctx->in_history)
+                       ev.rxpend_timestamp = ctx->in_history[ctx->in_head];
+
+               rtdm_lock_put_irqrestore(&ctx->lock, lock_ctx);
+
+               if (user_info)
+                       err =
+                           rtdm_safe_copy_to_user(user_info, arg, &ev,
+                                                  sizeof(struct
+                                                         rtser_event));
+                       else
+                               memcpy(arg, &ev, sizeof(struct rtser_event));
+
+wait_unlock_out:
+               /* release the simple event waiter lock */
+               clear_bit(0, &ctx->ioc_event_lock);
+               break;
+       }
+
+       case RTSER_RTIOC_BREAK_CTL: {
+               rtdm_lock_get_irqsave(&ctx->lock, lock_ctx);
+               rt_imx_uart_break_ctl(ctx, (int)arg);
+               rtdm_lock_put_irqrestore(&ctx->lock, lock_ctx);
+               break;
+       }
+
+#ifdef FIXME
+       case RTIOC_PURGE: {
+               int fcr = 0;
+
+               rtdm_lock_get_irqsave(&ctx->lock, lock_ctx);
+               if ((long)arg & RTDM_PURGE_RX_BUFFER) {
+                       ctx->in_head = 0;
+                       ctx->in_tail = 0;
+                       ctx->in_npend = 0;
+                       ctx->status = 0;
+                       fcr |= FCR_FIFO | FCR_RESET_RX;
+                       rt_imx_uart_reg_in(mode, base, RHR);
+               }
+               if ((long)arg & RTDM_PURGE_TX_BUFFER) {
+                       ctx->out_head = 0;
+                       ctx->out_tail = 0;
+                       ctx->out_npend = 0;
+                       fcr |= FCR_FIFO | FCR_RESET_TX;
+               }
+               if (fcr) {
+                       rt_imx_uart_reg_out(mode, base, FCR, fcr);
+                       rt_imx_uart_reg_out(mode, base, FCR,
+                                        FCR_FIFO | ctx->config.fifo_depth);
+               }
+               rtdm_lock_put_irqrestore(&ctx->lock, lock_ctx);
+               break;
+       }
+#endif
+
+       default:
+               err = -ENOTTY;
+       }
+
+       return err;
+}
+
+ssize_t rt_imx_uart_read(struct rtdm_dev_context *context,
+                        rtdm_user_info_t *user_info, void *buf, size_t nbyte)
+{
+       struct rt_imx_uart_ctx *ctx;
+       rtdm_lockctx_t lock_ctx;
+       size_t read = 0;
+       int pending;
+       int block;
+       int subblock;
+       int in_pos;
+       char *out_pos = (char *)buf;
+       rtdm_toseq_t timeout_seq;
+       ssize_t ret = -EAGAIN;  /* for non-blocking read */
+       int nonblocking;
+
+       if (nbyte == 0)
+               return 0;
+
+       if (user_info && !rtdm_rw_user_ok(user_info, buf, nbyte))
+               return -EFAULT;
+
+       ctx = (struct rt_imx_uart_ctx *)context->dev_private;
+
+       rtdm_toseq_init(&timeout_seq, ctx->config.rx_timeout);
+
+       /* non-blocking is handled separately here */
+       nonblocking = (ctx->config.rx_timeout < 0);
+
+       /* only one reader allowed, stop any further attempts here */
+       if (test_and_set_bit(0, &ctx->in_lock))
+               return -EBUSY;
+
+       rtdm_lock_get_irqsave(&ctx->lock, lock_ctx);
+
+       while (1) {
+               if (ctx->status) {
+                       if (testbits(ctx->status, RTSER_LSR_BREAK_IND))
+                               ret = -EPIPE;
+                       else
+                               ret = -EIO;
+                       ctx->saved_errors = ctx->status &
+                           (RTSER_LSR_OVERRUN_ERR | RTSER_LSR_PARITY_ERR |
+                            RTSER_LSR_FRAMING_ERR | RTSER_SOFT_OVERRUN_ERR);
+                       ctx->status = 0;
+                       break;
+               }
+
+               pending = ctx->in_npend;
+
+               if (pending > 0) {
+                       block = subblock = (pending <= nbyte) ? pending : nbyte;
+                       in_pos = ctx->in_head;
+
+                       rtdm_lock_put_irqrestore(&ctx->lock, lock_ctx);
+
+                       /* Do we have to wrap around the buffer end? */
+                       if (in_pos + subblock > IN_BUFFER_SIZE) {
+                               /* Treat the block between head and buffer end
+                                  separately. */
+                               subblock = IN_BUFFER_SIZE - in_pos;
+
+                               if (user_info) {
+                                       if (rtdm_copy_to_user
+                                           (user_info, out_pos,
+                                            &ctx->in_buf[in_pos],
+                                            subblock) != 0) {
+                                               ret = -EFAULT;
+                                               goto break_unlocked;
+                                       }
+                               } else
+                                       memcpy(out_pos, &ctx->in_buf[in_pos],
+                                              subblock);
+
+                               read += subblock;
+                               out_pos += subblock;
+
+                               subblock = block - subblock;
+                               in_pos = 0;
+                       }
+
+                       if (user_info) {
+                               if (rtdm_copy_to_user(user_info, out_pos,
+                                                     &ctx->in_buf[in_pos],
+                                                     subblock) != 0) {
+                                       ret = -EFAULT;
+                                       goto break_unlocked;
+                               }
+                       } else
+                               memcpy(out_pos, &ctx->in_buf[in_pos], subblock);
+
+                       read += subblock;
+                       out_pos += subblock;
+                       nbyte -= block;
+
+                       rtdm_lock_get_irqsave(&ctx->lock, lock_ctx);
+
+                       ctx->in_head =
+                           (ctx->in_head + block) & (IN_BUFFER_SIZE - 1);
+                       ctx->in_npend -= block;
+                       if (ctx->in_npend == 0)
+                               ctx->ioc_events &= ~RTSER_EVENT_RXPEND;
+
+                       if (nbyte == 0)
+                               break; /* All requested bytes read. */
+
+                       continue;
+               }
+
+               if (nonblocking)
+                       /* ret was set to EAGAIN in case of a real
+                          non-blocking call or contains the error
+                          returned by rtdm_event_wait[_until] */
+                       break;
+
+               ctx->in_nwait = nbyte;
+
+               rtdm_lock_put_irqrestore(&ctx->lock, lock_ctx);
+
+               ret = rtdm_event_timedwait(&ctx->in_event,
+                                          ctx->config.rx_timeout,
+                                          &timeout_seq);
+               if (ret < 0) {
+                       if (ret == -EIDRM) {
+                               /* Device has been closed -
+                                  return immediately. */
+                               return -EBADF;
+                       }
+
+                       rtdm_lock_get_irqsave(&ctx->lock, lock_ctx);
+
+                       nonblocking = 1;
+                       if (ctx->in_npend > 0) {
+                               /* Final turn: collect pending bytes
+                                  before exit. */
+                               continue;
+                       }
+
+                       ctx->in_nwait = 0;
+                       break;
+               }
+
+               rtdm_lock_get_irqsave(&ctx->lock, lock_ctx);
+       }
+
+       rtdm_lock_put_irqrestore(&ctx->lock, lock_ctx);
+
+break_unlocked:
+       /* Release the simple reader lock, */
+       clear_bit(0, &ctx->in_lock);
+
+       if ((read > 0) && ((ret == 0) || (ret == -EAGAIN) ||
+                          (ret == -ETIMEDOUT) || (ret == -EINTR)))
+               ret = read;
+
+       return ret;
+}
+
+static ssize_t rt_imx_uart_write(struct rtdm_dev_context *context,
+                                rtdm_user_info_t *user_info, const void *buf,
+                                size_t nbyte)
+{
+       struct rt_imx_uart_ctx *ctx;
+       rtdm_lockctx_t lock_ctx;
+       size_t written = 0;
+       int free;
+       int block;
+       int subblock;
+       int out_pos;
+       char *in_pos = (char *)buf;
+       rtdm_toseq_t timeout_seq;
+       ssize_t ret;
+
+       if (nbyte == 0)
+               return 0;
+
+       if (user_info && !rtdm_read_user_ok(user_info, buf, nbyte))
+               return -EFAULT;
+
+       ctx = (struct rt_imx_uart_ctx *)context->dev_private;
+
+       rtdm_toseq_init(&timeout_seq, ctx->config.rx_timeout);
+
+       /* Make write operation atomic. */
+       ret = rtdm_mutex_timedlock(&ctx->out_lock, ctx->config.rx_timeout,
+                                  &timeout_seq);
+       if (ret)
+               return ret;
+
+       while (nbyte > 0) {
+               rtdm_lock_get_irqsave(&ctx->lock, lock_ctx);
+
+               free = OUT_BUFFER_SIZE - ctx->out_npend;
+
+               if (free > 0) {
+                       block = subblock = (nbyte <= free) ? nbyte : free;
+                       out_pos = ctx->out_tail;
+
+                       rtdm_lock_put_irqrestore(&ctx->lock, lock_ctx);
+
+                       /* Do we have to wrap around the buffer end? */
+                       if (out_pos + subblock > OUT_BUFFER_SIZE) {
+                               /* Treat the block between head and buffer
+                                  end separately. */
+                               subblock = OUT_BUFFER_SIZE - out_pos;
+
+                               if (user_info) {
+                                       if (rtdm_copy_from_user
+                                           (user_info,
+                                            &ctx->out_buf[out_pos],
+                                            in_pos, subblock) != 0) {
+                                               ret = -EFAULT;
+                                               break;
+                                       }
+                               } else
+                                       memcpy(&ctx->out_buf[out_pos], in_pos,
+                                              subblock);
+
+                               written += subblock;
+                               in_pos += subblock;
+
+                               subblock = block - subblock;
+                               out_pos = 0;
+                       }
+
+                       if (user_info) {
+                               if (rtdm_copy_from_user
+                                   (user_info, &ctx->out_buf[out_pos],
+                                    in_pos, subblock) != 0) {
+                                       ret = -EFAULT;
+                                       break;
+                               }
+                       } else
+                               memcpy(&ctx->out_buf[out_pos], in_pos, block);
+
+                       written += subblock;
+                       in_pos += subblock;
+                       nbyte -= block;
+
+                       rtdm_lock_get_irqsave(&ctx->lock, lock_ctx);
+
+                       ctx->out_tail =
+                           (ctx->out_tail + block) & (OUT_BUFFER_SIZE - 1);
+                       ctx->out_npend += block;
+
+                       ctx->ier_status |= IER_TX;
+                       rt_imx_uart_start_tx(ctx);
+
+                       rtdm_lock_put_irqrestore(&ctx->lock, lock_ctx);
+                       continue;
+               }
+
+               rtdm_lock_put_irqrestore(&ctx->lock, lock_ctx);
+
+               ret = rtdm_event_timedwait(&ctx->out_event,
+                                          ctx->config.tx_timeout,
+                                          &timeout_seq);
+               if (ret < 0) {
+                       if (ret == -EIDRM) {
+                               /* Device has been closed -
+                                  return immediately. */
+                               return -EBADF;
+                       }
+                       if (ret == -EWOULDBLOCK) {
+                               /* Fix error code for non-blocking mode. */
+                               ret = -EAGAIN;
+                       }
+                       break;
+               }
+       }
+
+       rtdm_mutex_unlock(&ctx->out_lock);
+
+       if ((written > 0) && ((ret == 0) || (ret == -EAGAIN) ||
+                             (ret == -ETIMEDOUT) || (ret == -EINTR)))
+               ret = written;
+
+       return ret;
+}
+
+static const struct rtdm_device __initdata device_tmpl = {
+       .struct_version         = RTDM_DEVICE_STRUCT_VER,
+
+       .device_flags           = RTDM_NAMED_DEVICE | RTDM_EXCLUSIVE,
+       .context_size           = sizeof(struct rt_imx_uart_ctx),
+       .device_name            = "",
+
+       .open_nrt               = rt_imx_uart_open,
+
+       .ops = {
+               .close_nrt      = rt_imx_uart_close,
+               .ioctl_rt       = rt_imx_uart_ioctl,
+               .ioctl_nrt      = rt_imx_uart_ioctl,
+               .read_rt        = rt_imx_uart_read,
+               .write_rt       = rt_imx_uart_write,
+       },
+
+       .device_class           = RTDM_CLASS_SERIAL,
+       .device_sub_class       = RTDM_SUBCLASS_16550A,
+       .profile_version        = RTSER_PROFILE_VER,
+       .driver_name            = DRIVER_NAME,
+       .driver_version         = RTDM_DRIVER_VER(1, 0, 0),
+       .peripheral_name        = "IMX UART",
+       .provider_name          = "Wolfgang Grandegger",
+};
+
+static int rt_imx_uart_probe(struct platform_device *pdev)
+{
+       struct imxuart_platform_data *pdata;
+       struct rtdm_device *dev;
+       struct rt_imx_uart_port *port;
+       struct resource *res;
+       int err;
+
+       port = kzalloc(sizeof(*port), GFP_KERNEL);
+       if (!port)
+               return -ENOMEM;
+
+       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+       if (!res) {
+               err = -ENODEV;
+               goto kfree_out;
+       }
+       port->mapbase = res->start;
+
+       port->irq = platform_get_irq(pdev, 0);
+       if (port->irq <= 0) {
+               err = -ENODEV;
+               goto kfree_out;
+       }
+
+       if (!request_mem_region(port->mapbase, PAGE_SIZE, DRIVER_NAME)) {
+               err = -EBUSY;
+               goto kfree_out;
+       }
+
+       port->membase = ioremap(port->mapbase, PAGE_SIZE);
+       if (!port->membase) {
+               err = -ENOMEM;
+               goto release_mem_region_out;
+       }
+
+
+       dev = &port->rtdm_dev;
+       memcpy(dev, &device_tmpl, sizeof(struct rtdm_device));
+       snprintf(dev->device_name, RTDM_MAX_DEVNAME_LEN, "rtser%d",
+                start_index + pdev->id);
+       dev->device_id = pdev->id;
+       dev->device_data = port;
+
+       dev->proc_name = dev->device_name;
+
+       if (!tx_fifo[pdev->id] || tx_fifo[pdev->id] > TX_FIFO_SIZE)
+               port->tx_fifo = TX_FIFO_SIZE;
+       else
+               port->tx_fifo = tx_fifo[pdev->id];
+
+       port->clk = clk_get(&pdev->dev, "uart");
+       if (IS_ERR(port->clk)) {
+               err = PTR_ERR(port->clk);
+               goto iounmap_out;
+       }
+       clk_enable(port->clk);
+       port->uartclk = clk_get_rate(port->clk);
+
+       port->use_hwflow = 1;
+
+       pdata = pdev->dev.platform_data;
+       if (pdata && (pdata->flags & IMXUART_HAVE_RTSCTS))
+               port->have_rtscts = 1;
+       if (pdata && (pdata->flags & IMXUART_USE_DCEDTE))
+               port->use_dcedte = 1;
+       if (pdata && pdata->init) {
+               err = pdata->init(pdev);
+               if (err)
+                       goto clk_disable_out;
+       }
+
+       err = rtdm_dev_register(dev);
+       if (err)
+               goto pdata_exit_out;
+
+       platform_set_drvdata(pdev, port);
+
+       printk(KERN_INFO
+              "%s on IMX UART%d: membase=0x%p mapbase=%#x irq=%d uartclk=%d\n",
+              dev->device_name, pdev->id, port->membase, (u32)port->mapbase,
+              port->irq, port->uartclk);
+
+       return 0;
+
+pdata_exit_out:
+       if (pdata && pdata->exit)
+               pdata->exit(pdev);
+clk_disable_out:
+       clk_put(port->clk);
+       clk_disable(port->clk);
+iounmap_out:
+       iounmap(port->membase);
+release_mem_region_out:
+       release_mem_region(port->mapbase, SZ_4K);
+kfree_out:
+       kfree(port);
+
+       return err;
+}
+
+static int rt_imx_uart_remove(struct platform_device *pdev)
+{
+       struct imxuart_platform_data *pdata;
+       struct rt_imx_uart_port *port = platform_get_drvdata(pdev);
+       struct rtdm_device *dev = &port->rtdm_dev;
+
+       pdata = pdev->dev.platform_data;
+       platform_set_drvdata(pdev, NULL);
+
+       rtdm_dev_unregister(dev, 1000);
+
+       if (port->clk) {
+               clk_put(port->clk);
+               clk_disable(port->clk);
+       }
+
+       if (pdata && pdata->exit)
+               pdata->exit(pdev);
+
+       iounmap(port->membase);
+       release_mem_region(port->mapbase, PAGE_SIZE);
+       kfree(port);
+
+       return 0;
+}
+
+static const struct platform_device_id rt_imx_uart_id_table[] = {
+       {"imx-uart",},
+       {},
+};
+
+static struct platform_driver rt_imx_uart_driver = {
+       .probe = rt_imx_uart_probe,
+       .remove = rt_imx_uart_remove,
+       .id_table = rt_imx_uart_id_table,
+       .driver = {
+               .name = DRIVER_NAME,
+               .owner = THIS_MODULE,
+       },
+};
+
+static int __init rt_imx_uart_init(void)
+{
+       return platform_driver_register(&rt_imx_uart_driver);
+}
+
+static void __exit rt_imx_uart_exit(void)
+{
+       platform_driver_unregister(&rt_imx_uart_driver);
+}
+
+module_init(rt_imx_uart_init);
+module_exit(rt_imx_uart_exit);
+
+MODULE_AUTHOR("Wolfgang Grandegger <w...@denx.de>");
+MODULE_DESCRIPTION("IMX RTserial port driver");
+MODULE_LICENSE("GPL");


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